The present invention relates to a method and a structure of a commutator segment for connecting armature coils to commutator segments, and more particularly to a commutator in which conductors are physically connected by plastic-deforming components of an armature.
A typical method for plastic-deforming the components of the armature to physically connect the conductors is disclosed in Japanese Patent Application Laid-open No. 131705/79. In the disclosed method, in the inner walls of a slot of each commutator segment, to which the sides of an upper armature coil oppose, axially extending recesses are formed, and the upper coil is radially pressed to cause a plastic flow thereof into the recesses and to couple it to a lower coil. However, since the lower coil is mounted on the flat base of the slot, a sufficient stress is not applied to the lower coil when the upper coil is pressed and hence the slot is not filled. As a result, a contact resistance between the conductors increases, which is disadvantageous in electrical sense. Although coil material entered into the recesses of the inner wall of the slot provides a sufficient force to prevent a radial escapement of the armature coil, a force to prevent an axial escapement of the armature coil results from only friction forces between the coils and the commutator segment and between the coils. Accordingly, a sufficient mechanical strength is not attained.